Tesla Motors CEO Elon Musk tweeted Tuesday that the company was narrowly cash flow positive last week. Tesla Motors achieved profitability in 2009, but that didn't continue, and it's unlikely to continue this time--at least in the short term, Ingram writes.

The body of a Tesla Model S is transported by an automated crane at the Tesla factory in Fremont, Calif., in this October 2011 file photo. News that Tesla Motors was cash flow positive last week is music to the ears of Tesla fans, Ingram writes.

No doubt the news is music to the ears of Tesla fans, not to mention Musk himself--but at the same time, it's important to put things in context.

While Musk expects things to improve further, this is still only one week. As such, it's a minor success, rather than a major one--and Musk no doubt knows that there's still a lot of hard work to come.

Tesla's expenditure will increase as it ramps up production, and needs to deliver cars quickly to cover its costs. Tesla has also had to delay production this year, owing to delays in acquiring parts from suppliers. Small setbacks like this aren't uncommon, and will ultimately lead to fluctuating profitability.

We've been here before, of course. Tesla achieved profitability back in 2009 while it was building the Roadster--but that didn't continue, and it's unlikely to continue this time--at least in the short term.

It's certainly not an insurmountable challenge, but the message here is simple: positive cash flow won't necessarily stay that way.

One swallow does not make a summer...

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